The present invention relates to a novel method of making siloxane-based polyamides.
There is a growing demand in the personal care arena for polymeric materials capable of thickening dimethylcyclosiloxanes in order to modify product viscosity in various market niche hair, skin, cosmetic, and underarm, applications.
The '709 application is directed to one type of a process for preparing siloxane-based polyamides. The process according to the '709 application involves many steps, and this results in cost prohibitive products which are difficult to produce in commercial quantity.
For example, in the '709 application process, a dimethyl hydride endblocked polydimethylsiloxane is first prepared containing the appropriate number of siloxane units to achieve a desired value of DP. The carboxylic acid group of undecylenic acid is then protected through reaction with hexamethyldisilazane. The dimethyl hydride endblocked polydimethylsiloxane and the protected undecylenic acid are reacted to produce a siloxane diacid, i.e., a carboxydecyl terminated polydimethylsiloxane. This reaction is accomplished in the presence of a platinum catalyst, and the product is washed with methanol to remove the trimethylsilyl protecting group from the protected siloxane diacid. The siloxane diacid is then reacted with an organic diamine to produce a siloxane-based polyamide.
Accordingly, a new process has been discovered herein that eliminates many of the otherwise costly steps involved in the process according to the '709 application.
The new process basically involves the addition of an olefinic acid with an organic diamine to produce an organic diamide. Once the olefinic acid and the organic diamine are fully reacted, an .tbd.SiH endblocked polysiloxane is added in the presence of a platinum catalyst, to produce a siloxane-based polyamide via hydrosilylation. The resulting polymeric product is in the form of a high molecular weight thermoplastic polymer. The benefits of this process is that it allows for the production of a cost effective manufactured product in commercial quantity.